1. Field of the Invention
This invention relates to seal structures and methods for sealing between the outer cylindrical surface of a floating member and the inner bore of a surrounding conduit in a well bore.
2. Background Information
It is often desirable in well bore operations to provide a seal between a floating member and the surrounding conduit in a well bore. For instance, the floating member could be part of a thermal expansion joint in a thermal well. The floating member could also be a locator type seal assembly in a traditional permanent packer installed within a well bore. Other so-called "slide joints" are used to space out connecting strings between multi-string packets.
The seal structure of the present invention has particular advantages in thermal well environments. By "thermal well" is meant a well having a bottom hole temperature in excess of about 400 degrees Fahrenheit. Where downhole equipment is subject to high temperatures, such as in thermal wells, it is desirable for the tubing string extending to the well surface to be movable longitudinally relative to the outer packer which is sealed and anchored to the surrounding well conduit, without unseating the packer. This longitudinal movement allows for contraction and expansion of the tubing string due to temperature changes in the well bore.
In the thermal well environment, it is often necessary to provide a seal material for sealing between the slide joint and the surrounding well conduit which is made from a material other than a traditional elastomer. For instance, suitable seal or packing materials are known which are comprised of asbestos or synthetic polymers. In order to run a packing or seal of such a material into the bore of the surrounding well conduit, it is desirable to have less than an interference fit during insertion. It is then desirable to energize the seal in some manner to provide a fluid tight seal between the exterior of the floating member and the inner bore of the surrounding conduit.